Elevation of a novel pituitary protein (7B2) in the plasma in small cell carcinoma of the lung

Abstract

7B 2 is a new protein isolated from human pituitary glands and distributed widely, particularly with high concentrations in the neuroendocrine tissues in the rat. We measured plasma 7B 2 concentrations in 333 normal subjects, 20 patients with benign pulmonary disease and 111 patients with primary lung cancer ( 21 small cell carcinoma, 90 non-small cell carcinoma). A normal range for plasma 7B 2 concentrations was defined as less than the mean + 3 S.D. value ( 110 pg/ml) based on plasma 7B 2 concentrations in 333 normal subjects. Elevation of the plasma 7B 2 concentration over the normal range was observed in 15 of 21 patients ( 71.4%) with small cell carcinoma, eight of 90 ( 8.9%) with non-small cell carcinoma and four of 20 ( 20%) with benign pulmonary disease. Plasma 7B 2 concentrations correlated with the clinical course on chemotherapy in some patients with small cell carcinoma. Immunocytochemical studies revealed numerous 7B 2-positive cells in the small cell carcinoma specimen, while 7B 2 staining was not observed in the non-small cell carcinoma and the normal lung specimens. These findings suggest that 7B 2 is secreted by the small cell carcinoma of the lung, which caused elevation of plasma 7B 2 in these patients. 7B 2 might be a possible plasma tumor marker for the small cell carcinoma of the lung.